1. Field of the Invention
The present invention relates to low temperature-stable creamy wash compositions. The present invention also relates to methods of preparing such a composition. The present invention further relates to methods of washing with such a composition.
2. Discussion of the Background
It has been long known that N-long-chain-acyl acidic amino acids and/or salts thereof are useful as less irritating materials in comparison with a skin or hair wash containing an anionic surfactant such as an alkyl sulfate or an alkyl sulfonate as an active ingredient, which has been generally used.
When an N-long-chain-acyl acidic amino acid and/or a salt thereof having high safety is used in a creamy wash composition of a cleansing foam, a makeup remover, or the like, it has been known that a composition is obtained by containing an N-long-chain-acyl acidic amino acid and/or a salt thereof, a polyhydric alcohol, and water, as essential ingredients (see, JP-A-62-124200). However, such a creamy wash composition is problematic in that it becomes hard at a low temperature and tends to separate at a high temperature. Accordingly, it has not necessarily been said to be a low temperature-stable creamy wash composition.
An example of an approach to eliminate the problem of a creamy wash composition becoming hard at a low temperature is the use of a 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine as an ampholytic surfactant in combination with an N-long-chain-acyl acidic amino acid and a polyhydric alcohol (see, JP-A-1-294799). However, it still becomes hard when stored at a low temperature, and no satisfactory low temperature-stable creamy wash composition has been obtained.
Thus, there remains a need for a low temperature-stable creamy wash composition which contains an N-long-chain-acyl acidic amino acid and/or a salt thereof and a polyhydric alcohol as active ingredients and which is excellent in low temperature stability, without impairment of the foaming properties and/or deterioration of the feeling upon use.